CHAPTER 24: INTRINSIC DEFECTS LEADING TO INCREASED ERYTHROCYTE DESTRUCTION

Question 1

(1) In HS a characteristic abnormality in the CBC results is:

a. Increased MCV
b. Increased MCHC
c. Decreased MCH
d. Decreased platelet and WBC counts

Answer 1

b. Increased MCHC

Question 2

(2) The altered shape of the spherocyte in HS is due to:

a. An abnormal RBC membrane protein affecting vertical protein interactions
b. Defective RNA synthesis
c. An extrinsic factor in the plasma
d. Abnormality in the globin composition of the hemoglobin molecule

Answer 2

a. An abnormal RBC membrane protein affecting vertical protein interactions

Question 3

(3) Which of the following results are consistent with HS?

a. Increased osmotic fragility, negative DAT result
b. Decreased osmotic fragility, positive DAT result
c. Increased osmotic fragility, positive DAT result
d. Decreased osmotic fragility, negative DAT result

Answer 3

a. Increased osmotic fragility, negative DAT result

Question 4

(4) The RBCs in HE are abnormally shaped and have unstable cell membranes as a result of:

a. Abnormal shear stresses in the circulation
b. Defects in horizontal membrane protein interactions
c. Mutations in ankyrin
d. Lack of all Rh antigens in the RBC membrane

Answer 4

b. Defects in horizontal membrane protein interactions

Question 5

(5) The peripheral blood film for patients with mild HE is characterized by:

a. Elliptical RBCs
b. Oval RBCs with one or two transverse ridges
c. Overhydrated RBCs with oval central pallor
d. Densely stained RBCs with a few irregular projections

Answer 5

a. Elliptical RBCs

Question 6

(6) Laboratory test results for patients with HPP include all of the following except:

a. RBCs that show marked thermal sensitivity at 41° C to 45° C
b. Marked poikilocytosis with elliptocytes, RBC fragments, and microspherocytes
c. Low fluorescence when incubated with eosin-5’-maleimide
d. Increased MCV and normal RDW

Answer 6

d. Increased MCV and normal RDW

Question 7

(7) Acanthocytes are found in association with:

a. Abetalipoproteinemia
b. G6PD deficiency
c. Rh deficiency syndrome
d. Vitamin B12 deficiency

Answer 7

a. Abetalipoproteinemia

Question 8

(8) The most common manifestation of G6PD deficiency is:

a. Chronic hemolytic anemia caused by cell shape change
b. Acute hemolytic anemia caused by drug exposure or infections
c. Mild compensated hemolysis caused by ATP deficiency
d. Chronic hemolytic anemia caused by intravascular RBC lysis

Answer 8

b. Acute hemolytic anemia caused by drug exposure or infections

Question 9

(9) A patient experiences an episode of acute intravascular hemolysis after taking primaquine for the first time. The physician suspects that the patient may have G6PD deficiency and orders an RBC G6PD assay 2 days after the hemolytic episode begins. How will this affect the test result?

a. No effect
b. False increase due to reticulocytosis
c. False decrease due to hemoglobinemia
d. Absence of enzyme activity

Answer 9

b. False increase due to reticulocytosis

Question 10

(10) The most common defect or deficiency in the anaerobic glycolytic pathway that causes chronic HNSHA is:

a. Pyruvate kinase deficiency
b. Lactate dehydrogenase deficiency
c. Glucose-6-phosphate dehydrogenase deficiency
d. Methemoglobin reductase deficiency

Answer 10

a. Pyruvate kinase deficiency

Question 11

(11) Which of the following laboratory tests would be best to confirm PNH?

a. Acidified serum test (Ham test)
b. Osmotic fragility test
c. Flow cytometry for detection of eosin-5’-maleimide binding on erythrocytes
d. Flow cytometry for detection of CD55, CD59, and FLAER binding on neutrophils and monocytes

Answer 11

d. Flow cytometry for detection of CD55, CD59, and FLAER binding on neutrophils and monocytes